Software Defined Radio (SDR) systems are adaptable to many different protocols, and operate over a wide range of different RF bands having varying channel spacing. As the prevalence of multi-band, multi-protocol SDR systems has increased, use requirements have expanded to include the capability of simultaneously receiving multiple RF signals. Each RF signal is composed of complex IQ signals and is transmitted over its own unique channel. Each channel is able to be spectrally located within any band of operation as may be appropriate for the SDR application.
A Direct Conversion Receiver (DCR) is ideally suited for SDR applications due to its relatively low cost, small size, and operational flexibility over a wide range of channel spacing and RF bands. A receiver may be referred to as a DCR if the down conversion mixer (also referred to as a down mixer) is sourced by a Local Oscillator (LO) having a frequency approximately equal to the desired RF carrier frequency. A DCR receiver may also include receiver systems where the frequency difference between the LO and the desired RF carrier signal is less than a specified bandwidth (BW) typically below 1 MHz to 2 MHz, which may also be called a Very Low Intermediate Frequency (VLIF) configuration for the DCR topology. Conventional SDR architectures support simultaneous reception of multiple RF signals over multiple RF channels by incorporating parallel, stand-alone receivers for each RF channel being monitored. However, the use of parallel receivers is generally expensive and consumes an increased amount of power, as well as incurring a significant size penalty to accommodate the multiple receivers.
It is desirable to create a Hybrid DCR (H-DCR) configuration to simultaneously receive RF signals on multiple RF channels without incurring significant cost and size penalties.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments shown so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Other elements, such as those known to one of skill in the art, may thus be present.